Treatment of hydrocarbons



Sept. 5, 1944; H. s'. BLOCH TREATMENT OF HYDROCARBONS Filed Oct. 19,1940 INVENTOR HERMAN S BLOCH ATTORNEY Patented Sept. 5, 1944 UNITEDSTATES PATENT OFFICE TREATMENT OF HYDBOCABBONS Herman S. Bloch, Chicago,111., assignor to Universal Oil Products Company, Chicago, 111., acorporation of Delaware v Application October 19, 194% Serial No.361,809

4 Claims. (Cl. 196-54) This invention relates to the treatment ofhydrocarbon oils comprising essentially paraflins and naphthenes andpreferably relatively free from oleflns and aromatics, to producetherefrom lower boiling hydrocarbons, chiefly isoparaflins.

In a more specific sense the invention is concemed with a process forconverting a hydromore reactive than the corresponding normalhydrocarbons and consequently these may be utilized in the production ofother branched chain paraflins by so-called alkylation reactions in thepresence of suitable catalysts. Also, lower boiling isoparafllns, suchas isobutane and isopentane, may be dehydrogenated to the correspondingbranched chain oleflns which in turn may be converted into normallyliquid polymers hydrogenatable by hydrogen-containing gases derived fromthe dehydrogenation step to produce substantially saturated motor fuelof high antiknock value.

In one specific embodiment the present invention comprises a process forconverting a substantially saturated hydrocarbon oil into substantialyields of a light hydrocarbon fraction rich in isobutane and asubstantially saturated gasoline of high octane number which comprisestreating said hydrocarbon oil with hydrogen in the presence of a mixtureof boron fluoride and hydrogen fluoride to form reaction products;separating said reaction products into a light hydrocarbon fraction richin isobutane, a substantially saturated gasoline, a recycle oil, and atar; returning said recycle oil to commingle with the hydrocarbon oilbeing charged to the process; directing'said tar to a subsequenttreatment in the presence of hydrogen at a relatively higher temperatureto decompose said tar and form light hydrocarbons and a mixturecomprising essentially boron fluoride, hydrogen, and hydrogen fluoride;and recycling said mixture to commingle with the hydrocarbons beingcharged to the process.

The substantially saturated hydrocarbons com- Furthermore, the branchedchain in considerable quantities in the oil-refining in dustry fromparaflinic, naphthenic, and mixed base crudes. Further, paraflins occurin substantial amounts in other gasolines and in the higher boilingconstituents of natural gas commonly lmown as casing head gasolinefincertain hydrocarbon materials produced synthetically, and in gasolinesproduced in relatively high yields by the cracking of relatively heavypetroleum fractions. In the case of cracked gasolines produced fromparailinic and naphthenic oils, the relative proportions of iso, normalparailins, and naphthenes may vary over a considerable range.

The preferred catalyst suitable for use in effecting the process of thepresent invention comprises essentially a mixture of boron trifluorideand hydrogen fluoride. Boron trifluoride, BFs, is normally a colorlessgas, having a boiling point. of -l0l C. and a melting point of -120 C.so that it is most readily handled for catalytic work in a vaporouscondition. Hydrogen fluoride has a boiling point of +20 C. and thereforethe proposed catalytic mixture of these compounds is readily employed invapor phase reactions or for the treatment of hydrocarbons in liquidphase under selected conditions of temperature and pressure. Inaccordance with the present invention, it has been found that variousproportioned mixtures of boron trifluoride and hydrogen fluoride havecatalytic effects in destructive hydrogenation of hydrocarbon oils toproduce lower boiling isoparaflinic hydrocarbons so that there isobviously a joint promoting action although it is recognized thatpromoter catalysis is not understood entirely and the term is sometimesabused. As a rule the amount of boron trifluoride is in excess of thehydrogen fluoride in the most efllcient mixtures, but this is not to betaken as an the absence of added hydrogen but under a superatmosphericpressure of another gas such as nitrogen. Also the desired conversion togaseous and liquid isoparaflins does not occur to a substantial degreewhen hydrogen fluoride and boron fluoride are used singly. In order toobtain the desired destructive hydrogenating action, it .is necessarythat hydrogen fluoride and boron fluoride be employed simultaneously. 1

The process of the present invention comprises essentially two stages,namely, (1) destructive hydrogenation of a substantially saturatedhydrocarbon ofl in the presence of boron fluoride and hydrogen fluorideto produce a light fraction containing isobutane and higher boilingisoparafllns and a relatively heavy fraction or tar containing asubstantial proportion of the hydrogen fluoride and boron fluorideutilized as catalyst; and (2) a subsequent treatment of said tar with orwithout addition of more hydrogen under .more severe conditions oftemperature and pressure. In the first stage of the process thetemperature, pressure, and time of contact necessary for effecting anoptimum amount of destructive hydrogenation will vary with thecomposition of the reaction mixture so that only broad ranges for theseoperating conditions need be given. In general, the temperature employedin treating both the primary charging stock and the tar is within theapproximate limits of 50 and-350 C. while the pressure is fromsubstantially atmospheric to approximately 2000 pounds per square inch.When desired, boron fluoride may be employed together with water whichcauses hydrolysis and thereby generates hydrogen fluoride in situ,

Destructive hydrogenation products formed as hereinabove set forth areseparated by fractional distillation into hydrogen, hydrogen fluoride,and bo'ron'fluoride catalyst, a light hydrocarbon fraction containingisobutane, a substantially saturated gasoline, a higher boiling recycleoil, and a residue or tar which is sub- .lected to further treatment ashereinafter set forth. The light fraction containing isobutane and asubstantially saturated gasoline fraction are conducted to storage whilethe recovered mixture of hydrogen, hydrogen fluoride, and boron fluorideand also the recycl oil are returned to further destructivehydrogenating treatment. The relatively high boiling residue or targenerally containing a substantial proportion of hydrogen fluoride andboron fluoride is subjected to a further treatment with hydrogen in thepresence or absence of additional boron fluoride and/or hydrogenfluoride and under sufficiently severe conditions of temperature andhydrogen pressure to convert into light hydrocarbons a substantialproportion of the tar and to regenerate the boron fluoride and hydrogenfluoride contained therein.

The accompanying drawing is essentially a flow diagram embodyingconventional apparatus for illustrating one specific combination ofsteps contemplated by the invention for producing isobutane and normallyliquid isoparaflins of gasoline boiling range from a relatively higherboiling hydrocarbon oil comprising essentially paraflins andnalphthenes, and preferably relatively free from olefins and aromatics.

Referring to the drawing, a hydrocarbon oil comprising essentiallyparamns and naphthenes is introduced through line I and valve 2 to pump3 which discharges through line 4 and valve 5 into reactor 6.Simultaneously hydrogen is directed through line I and valve 8 tocompressor 9 which discharges through line I0 and valve H into line 4,already mentioned. Also. boron fluoride is introduced through-line i2and valve I! to pump l4 which discharges through line l5 and valve l6into line "I in which the hydrogen and boron fluoride are commingledwith hydrogen fluoride introduced thereto by way of line 11, valve [8,pump 19, and line containing valve 2|. The commingled mixture ofhydrocarbon oil, boron fluoride, hydrogen fluoride, and hydrogen inreactor 6 is subjected to a temperature within the approximate limits of50 and 350 C. under a pressure of from substantially atmospheric toapproximately 2000 poundsper square inch for a time sufllcient toconvert a substantial proportion of the hydrocarbon oil into a mixturecomprising essentially isobutane, higher boiling isoparaflinichydrocarbons of motor fuel boiling range, and higher boiling productstogetherwith the catalyst and added hydrogen.

From reactor 6 the entire reaction mixture is directed through line 22and valve 23 to fractionator 24 of conventional design adequate toseparate a mixture of hydrogen and boron fluoride, a light hydrocarbonfraction containing isobutane, a substantial gasoline fraction, andrecycle oil and a residue or tar from which may be recovered gaseoushydrocarbons, hydrogen fluoride, and boron fluoride. The mixture ofrecovered hydrogen and boron fluoride is directed from fractionator 24through line 25 and valve 26 to compressor 21, next through line 28,valve 29, lines 65 and 4, and thence to reactor 8, already mentioned. Amixture of hydrogen fluoride and light gases containing isobutane isdirected from fractionator 24 through line 30 and valve 3| to separator32 of adequate design for separating the lighter hydrocarbon layer fromthe generally heavier liquefied hydrogen fluoride. Said .lighthydrocarbons are directed from separator 32 through line 33 and valve 34to storage, fractional distillation, or other treatment as desired.

Used hydrogen fluoride recovered by separation from the destructivehydrogenation products in separator 32 is withdrawn therefrom throughline 35 and valve 36 to pump or compressor 37 which discharges throughline 38 and valve 39 into line 4, already mentioned, through which thehydrocarbon fraction charged is introduced to the process. The gasolinefraction is directed from fractionator 24 through line 40 and valve 4|to storage. A higher boiling recycle oil is conducted from 'fractionator24 through line 42 and valve 43 to pump 44 which discharges through line45 and valve 46 to line 38, already mentioned, and is therein recycledto line 4 and thence to destructive hydrogenating reactor 6, alreadymentioned.

Heavy residual hydrocarbons and tar are directed from the bottom offractionator 24 through line 41 and valve 48 to pump 49 which dischargesthrough line 50, valve 5|, and line 52 into tar reactor 54 whichcomprises asuitable chamber operating preferably at a slightly highertemperature than reactor 6, although within the same general limits ofabout 50 and about 350 0., and in the presence of fresh hydrogensupplied from line "I through line 52 and valve 53 either at the samepressure as that utilized in reactor 8 or at'a higher pressure. The

- hydrogen being directed to reactor '54 through .line 52 may becommlngled therein with boron fluoride supplied from line [5 by way ofbranch conducted tromline 20 through branch line 51 and valve 58. Also,when desired, reactor 54 may be supplied, by means not shown, withadditionalquantities of hydrogen fluoride and/or boron fluoride derivedfrom the products of reactor 6.

In reactor 54 the residue or tar from the destructive hydrogenationtreatment in reactor 6 is converted into hydrogen fluoride and/or boronfluoride together light hydrocarbon gases, a considerable proportion ofwhich is isobutane. The hydrocarbon products from reactor 54 aredirected therefrom through line 59 and valve 60 to fractionator 6|tionators in which a mixture of hydrogen, hydrogen fluoride, and boronfluoride is separated from a light hydrocarbon fraction containingisobutane. Said mixture of hydrogen, hydrogen fluoride, and boronfluoride is directed from fractionator 6| through line 62 and valve 63to compressor 64 which discharges through line 65 and valve 66 into line4, already mentioned, through which the charged hydrocarbon oil andadmixed hydrogen, hydrogen fluoride, and boron fluoride are conducted todestructive hydrogenation in reactor 6. The light hydrocarbon fractionseparated as bottoms in fractionator 6| is directed through line 61 andvalve 68 to line 33, already mentioned, through which a similar lighthydrocarbon fraction produced in the destructive hydrogenation step isbeing conducted to storage. The products formed ihreactor 54 containsome difficultly volatile material such as relatively high boiling tarsand carbonaceous residues which are withdrawn from the bottom of reactor54 through line 69 and valve to waste or storage.

The following example is introduced as characteristic of the \practicaloperation of the process although it is not presented with the intentionof limiting the scope of the invention in exact correspondence with thenumerical data given:

A Pennsylvania gas oil, treated at 150 C. for

v 4 hours with 10% each of hydrogen fluoride and which consists ofeither a single fractionating column or a series of fracv 3 tiontreatment. With recycling of unconverted hydrocarbon oil the ultimateyields, based upon the weight of oil charged, are gasoline, 44%; gas

, .(75 mole per cent isobutane) 18%; and tar about 38%.

The tar produced in the first step and containing the major proportionof the hydrogen fluoride and boron fluoride is treated at 300 C. for 8hours under an initial hydrogen pressure of 100 atmospheres.Approximately 11% of the tar is converted in one pass into liquidhydrocarbons while hydrogen fluoride and boron fluoride are liberated tothe extent of 7.5 and 11%, respectively, of the quantities of thesematerials charged in the first step of the process. The remainders ofthe tar, hydrogen fluoride, and boron fluoride remain in the form of anunconverted residue.

The novelty and utility of the process of this invention are evidentfrom the preceding specification and example although neither section isintended to unduly limit its generally broad scope.

I claim as my invention:

1. A process for converting tar or residue containing boron fluoride andhydrogen fluoride into more useful products, which comprises subjectingsaid boron fluoride and hydrogen fluoride.

2. The process of claim 1 further characterized in that additional boronfluoride and hydrogen fluoride are added to said tar prior to theconversion treatment.

3. In a process for the conversion of substantially saturatedhydrocarbon oils wherein the oil is subjected. to conversion undercracking and isomerizing conditions of temperature and pressure in thepresence of :boron trifluoride, hydrogen fluoride and hydrogen andwherein a tar residue is formed comprising hydrocarbons, borontrifluoride and hydrogen fluoride, the method of treating the tarresidue which comprises subjecting said tar residue to the action ofhydrogen under more severe conditions of temperature and pressure thanare maintained in the first mentioned conversion step to liberate atleast a portion of said hydrocarbons, boron trifluoride and hydrogenfluoride from said residue. 7

4. The improved process of claim -3 further characterized in thatadditional boron trifluoride and hydrogen fluoride are introduced to thetar residue conversion step.

HERMAN S. BLOCH.

